From the Guidelines
This patient should undergo routine prenatal screenings and interventions, including standard first trimester laboratory testing and repeat Group B Streptococcus (GBS) screening at 36-37 weeks of this pregnancy, as GBS status can change between pregnancies. Given her previous GBS colonization, it is essential to retest for GBS colonization at 36-37 weeks gestation, as her previous GBS positive status does not automatically indicate prophylaxis for this pregnancy without retesting 1. The patient's previous GBS positive status and current pregnancy should be managed according to the CDC guidelines for prevention of perinatal Group B Streptococcal disease, which recommend routine screening for GBS colonization at 35-37 weeks gestation and intrapartum antibiotic prophylaxis for women with positive GBS screening results or other risk factors 1. Key interventions include:
- Standard first trimester laboratory testing, including complete blood count, blood type and antibody screen, rubella immunity, hepatitis B surface antigen, HIV, syphilis screening, and urine culture
- Repeat GBS screening at 36-37 weeks gestation
- Dating ultrasound to confirm gestational age
- Prenatal vitamins containing at least 400 mcg of folic acid daily
- First trimester genetic screening options, including cell-free DNA testing or combined first trimester screening
- Counseling on proper nutrition, exercise, and warning signs that require immediate medical attention
- Regular prenatal visits scheduled approximately every 4 weeks until 28 weeks, then every 2-3 weeks until 36 weeks, and weekly thereafter until delivery Intrapartum antibiotic prophylaxis regimens, as outlined in the CDC guidelines, should be considered for this patient if she is found to be GBS positive at 36-37 weeks gestation, with the recommended regimen being penicillin G, 5 million units IV initial dose, then 2.5-3.0 million units IV every 4 hours until delivery, or alternative regimens for patients with penicillin allergy 1.
From the Research
Group B Streptococcus Infection Prevention
- The patient's history of Group B Streptococcus (GBS) colonization during her previous pregnancy is a significant factor in determining the risk of GBS transmission to the newborn 2, 3.
- The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists recommend maternal intrapartum antibiotic prophylaxis (IAP) based on antenatal screening for GBS colonization to prevent perinatal GBS disease 2.
- Penicillin, ampicillin, or cefazolin are recommended for prophylaxis, with clindamycin and vancomycin reserved for cases of significant maternal penicillin allergy 2, 4.
Antibiotic Prophylaxis
- The optimal window for GBS screening is between 36 0/7 and 37 6/7 weeks of gestation, rather than beginning at 35 0/7 weeks' gestation 2.
- IAP is effective in preventing GBS early-onset disease, but there is no approach for the prevention of GBS late-onset disease 2, 3.
- The risk of early neonatal GBS infection increases in cases of preterm delivery, maternal fever during delivery, and membrane rupture more than 18 hours before delivery 3.
Management of Penicillin Allergy
- Pregnant women with a history of penicillin allergy are recommended to undergo skin testing to confirm or delabel the allergy, which can provide both short- and long-term health benefits 2.
- In cases of penicillin allergy, cefazolin and vancomycin are commonly used as alternative antibiotics for IAP 5.
- Antibiotic susceptibility testing is essential in guiding the choice of antibiotics for IAP in patients with penicillin allergy 4, 5.
Epidemiology and Outcomes
- The prevalence of maternal GBS colonization and the use of IAP can vary depending on the population and healthcare setting 6.
- The incidence of early-onset GBS disease can be reduced with the implementation of screening guidelines and IAP 3, 6.
- The risk of anaphylactic reaction to penicillin is a significant concern, and alternative antibiotics should be used in cases of penicillin allergy 3, 4.